Fibre optic communication systems have gained widespread acceptance over the past few decades. With the advent of optical fibre, communication signals are transmitted as light propagating along a fibre supporting total internal reflection of the light propagating therein. Many communication systems rely on optical communications because they are less susceptible to noise induced by external sources and are capable of supporting very high speed carrier signals and increased bandwidth. It was found that single mode optical communications systems support a higher rate of data transfer over longer distances. Consequently, single mode optical fibre is now a standard medium for transferring optical signals. Unfortunately, optical fibre components are bulky and often require hand assembly resulting in lower yield and higher costs. One modern approach to automating manufacture in the field of communications is integration. Integrated electronic circuits (ICs) are well known and their widespread use in every field is a clear indication of their cost effectiveness and robustness.
Presently, there is substantial promise in implementing waveguides and optical components within integrated waveguide material. These materials allow for integration of active and passive devices within a same physical substrate. These waveguides are typically formed in semiconductor material where they are often produced using layers of different material to provide a refractive index contrast between the waveguide core and its cladding. Alternatively, relative differences in dopant concentrations can provide small index differences that can be sufficient to provide guiding of an optical signal within a waveguide so formed.
Amongst the active devices that are manufactured into a same physical substrate as optical waveguides are laser sources. These laser sources are manufactured within the same substrate as the waveguide and thus advantageously allow for direct coupling from the laser source to the waveguide. Unfortunately, difficulties arise when these laser sources are manufactured within a same substrate. One such difficulty is forming end facets with the necessary optical qualities. Typically, the end facets of the laser are cleaved which provides a very high quality surface. Unfortunately, cleaving the laser to provide high quality end facets defeats the advantages sought in producing an integrated semiconductor optoelectronic circuit.
It would therefore be advantageous to provide a replacement for the cleaved end facet of the laser source to permit integration of the laser source within an optoelectronic substrate as well as to provide an improved reflection coefficient from the replaced end facet.